The crystal structure of the title compound C8H10N3+·ClO4-·C12H24O6·H2O, consists of an organic (1H-benzimidazol-2-yl)methanaminium cation, an inorganic ClO4- anion, one 18-crown-6 molecule and one water molecule. In the crystal, the cations and 18-crown-6 molecules are linked by N-HO hydrogen bonds. The crystal packing is stabilized by intermolecular O-HO, O-HN and O-HCl hydrogen bonds between anions and the water molecules. One 18-crown-6 C atom and a perchlorate O atom are disordered; both have an occupancy factor ratio of 0.60 (2) and 0.40 (2).

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